Ultrasound guidance versus conventional technique for radial arterial puncture in patients with shock in the emergency department: a randomized controlled trial

Abstract Background The benefit of ultrasound (US) guidance for arterial blood gas sampling has not been shown in non-preselected emergency department patients; however, it has been shown to be useful in difficult cases. Obtaining an arterial blood gas sample from the radial artery may be more challenging in patients with shock due to the difficulty in palpating the radial artery. The primary objective of this study was to compare first-attempt success between ultrasound-guided radial artery puncture and the conventional palpation technique for arterial blood gas sampling in patients presenting to the emergency department (ED) with shock. Methods This single-center, prospective, open-label randomized controlled trial included patients aged 18 years and older who presented to the ED of a university hospital with shock between October 1, 2024, and March 31, 2025. Participants were randomized into two groups: an ultrasound (US) group and a palpation (non-US) group. The primary outcome of the study was first-attempt success. Secondary outcomes included the number of attempts until successful puncture, time to successful puncture, and the need for a rescue femoral artery puncture. Results Of 106 patients assessed for eligibility, six were excluded because informed consent could not be obtained. The final study population consisted of 100 patients (50 in each group). First-attempt success was 30 (60%; 95% CI, 46.2% to 72.4%) in the non-US group and 47 (94%; 95% CI, 83.8% to 97.9%) in the US group. The absolute difference between groups was 34% (95% CI, 17.9% to 48.4%; p < 0.001). The median time to successful puncture was 17.5 s [12–22.8] in the US group and 35 s [23.5–50.0] in the non-US group (p < 0.001). Procedure failure requiring rescue femoral artery puncture was 8 (16%) in the non-US group and 2 (4%) in the US group (p < 0.05). No procedure-related complications were observed. Conclusions Ultrasound guidance for radial artery blood gas sampling in patients with shock is associated with higher first-attempt success rates and shorter times to successful puncture and may be a beneficial approach in this patient population. Trial registration ClinicalTrials.gov, NCT07362628, 23 January 2026.